From 35832b07b9faba9d2cd13431e16d6b874975c875 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Wed, 4 Jan 2023 19:57:33 +0100
Subject: [PATCH] UM Battery: basic support for LiPo cells

* Lipo cells (1S) should not be discharged below 3V
* LiPo cells have a different voltage/discharge rate curve
---
 usermods/Battery/battery_defaults.h   |  7 ++++++-
 usermods/Battery/readme.md            |  2 ++
 usermods/Battery/usermod_v2_Battery.h | 27 +++++++++++++++++++++++----
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/usermods/Battery/battery_defaults.h b/usermods/Battery/battery_defaults.h
index f1abe56c..c682cb45 100644
--- a/usermods/Battery/battery_defaults.h
+++ b/usermods/Battery/battery_defaults.h
@@ -18,7 +18,12 @@
 // https://batterybro.com/blogs/18650-wholesale-battery-reviews/18852515-when-to-recycle-18650-batteries-and-how-to-start-a-collection-center-in-your-vape-shop
 // Discharge voltage: 2.5 volt + .1 for personal safety
 #ifndef USERMOD_BATTERY_MIN_VOLTAGE
-  #define USERMOD_BATTERY_MIN_VOLTAGE 2.6f
+  #ifdef USERMOD_BATTERY_USE_LIPO
+    // LiPo "1S" Batteries should not be dischared below 3V !!
+    #define USERMOD_BATTERY_MIN_VOLTAGE 3.2f
+  #else
+    #define USERMOD_BATTERY_MIN_VOLTAGE 2.6f
+  #endif
 #endif
 
 #ifndef USERMOD_BATTERY_MAX_VOLTAGE
diff --git a/usermods/Battery/readme.md b/usermods/Battery/readme.md
index ea346a74..d55573ab 100644
--- a/usermods/Battery/readme.md
+++ b/usermods/Battery/readme.md
@@ -36,6 +36,7 @@ define `USERMOD_BATTERY` in `wled00/my_config.h`
 | Name                                            | Unit        | Description                                                                           |
 | ----------------------------------------------- | ----------- |-------------------------------------------------------------------------------------- |
 | `USERMOD_BATTERY`                               |             | define this (in `my_config.h`) to have this usermod included wled00\usermods_list.cpp |
+| `USERMOD_BATTERY_USE_LIPO`                      |             | define this (in `my_config.h`) if you use LiPo rechargeables (1S)                     |
 | `USERMOD_BATTERY_MEASUREMENT_PIN`               |             | defaults to A0 on ESP8266 and GPIO35 on ESP32                                         |
 | `USERMOD_BATTERY_MEASUREMENT_INTERVAL`          | ms          | battery check interval. defaults to 30 seconds                                        |
 | `USERMOD_BATTERY_MIN_VOLTAGE`                   | v           | minimum battery voltage. default is 2.6 (18650 battery standard)                      |
@@ -81,6 +82,7 @@ Specification from:  [Molicel INR18650-M35A, 3500mAh 10A Lithium-ion battery, 3.
 
 2023-01-04
 
+- basic support for LiPo rechargeable batteries ( `-D USERMOD_BATTERY_USE_LIPO`)
 - improved support for esp32 (read calibrated voltage)
 - corrected config saving (measurement pin, and battery min/max were lost)
 - various bugfixes
diff --git a/usermods/Battery/usermod_v2_Battery.h b/usermods/Battery/usermod_v2_Battery.h
index 7dbc4952..ac34a7e4 100644
--- a/usermods/Battery/usermod_v2_Battery.h
+++ b/usermods/Battery/usermod_v2_Battery.h
@@ -190,15 +190,30 @@ class UsermodBattery : public Usermod
       // calculate the voltage     
       voltage = ((rawValue / getAdcPrecision()) * maxBatteryVoltage) + calibration;
 #endif
-      // check if voltage is within specified voltage range
-      voltage = ((voltage<minBatteryVoltage) || (voltage>maxBatteryVoltage)) ? -1.0f : voltage;
+      // check if voltage is within specified voltage range, allow 10% over/under voltage
+      voltage = ((voltage < minBatteryVoltage * 0.85f) || (voltage > maxBatteryVoltage * 1.1f)) ? -1.0f : voltage;
 
       // translate battery voltage into percentage
       /*
         the standard "map" function doesn't work
         https://www.arduino.cc/reference/en/language/functions/math/map/  notes and warnings at the bottom
       */
-      batteryLevel = mapf(voltage, minBatteryVoltage, maxBatteryVoltage, 0, 100);
+      #ifdef USERMOD_BATTERY_USE_LIPO
+        batteryLevel = mapf(voltage, minBatteryVoltage, maxBatteryVoltage, 0, 100); // basic mapping
+        // LiPo batteries have a differnt dischargin curve, see 
+        //  https://blog.ampow.com/lipo-voltage-chart/
+        if (batteryLevel < 40.0f) 
+          batteryLevel = mapf(batteryLevel, 0, 40, 0, 12);       // last 45% -> drops very quickly
+        else {
+          if (batteryLevel < 90.0f)
+            batteryLevel = mapf(batteryLevel, 40, 90, 12, 95);   // 90% ... 40% -> almost linear drop
+          else // level >  90%
+            batteryLevel = mapf(batteryLevel, 90, 105, 95, 100); // highest 15% -> drop slowly
+        }
+      #else
+        batteryLevel = mapf(voltage, minBatteryVoltage, maxBatteryVoltage, 0, 100);
+      #endif
+      if (voltage > -1.0f) batteryLevel = constrain(batteryLevel, 0.0f, 110.0f);
 
       // if (calculateTimeLeftEnabled) {
       //   float currentBatteryCapacity = totalBatteryCapacity;
@@ -556,7 +571,11 @@ class UsermodBattery : public Usermod
      */
     void setMaxBatteryVoltage(float voltage)
     {
-      maxBatteryVoltage = max(getMinBatteryVoltage()+1.0f, voltage);
+      #ifdef USERMOD_BATTERY_USE_LIPO
+        maxBatteryVoltage = max(getMinBatteryVoltage()+0.7f, voltage);
+      #else
+        maxBatteryVoltage = max(getMinBatteryVoltage()+1.0f, voltage);
+      #endif
     }